Dust-collecting system



. HOWARD DUST COLLECT-ING SYSTEM March l2, 1929.

Filed April 28, 1927 4 Sheets-Sheet lQ/.llllllllq flor mura March Z, 1929. H. HOWARD DUST COLLECTING SYSTEM Filed April 28, l927 4 Sheets-Sheet attozmld.

March 12, 1929. v l-l.y HOWARD 1,705,449

DUST COLLECTING SYSTEM Filled April'ze, 192'? 4 sheets-sheet 3 March 12, 1929. H. HOWARD DUST' COLLECTING SYSTEM" 4 Sheets-Sheet 4 Filed Apri 1,28. 1927 SW1/wot:

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Patented Mar.- 12, 1.929"

' UNITED STATES HENRY HOWARD, OF CLEVELAND, OHIO, .ASSIGNOR TO THE GRASSELLI `.CHEIVIICLl COMPANY, OF CLEVELAND, OHIO, A CORPORATION F OHIO.

DUST-COLLECTING SYSTEM.

Application filed April 28,

This invention relates to a device for re; moving the dust, .fumc, and smoke from the exterior' or metallurgical furnaces, such as zinc smelting furnaces ofthe Belgian retort type.

These furnaces'are .usually arranged in blocks, a block lleing, for example, 110 feet long b v l to 20 feet wide and from l() to l2 feet high, the Zinc retorts being set into the .furnace on the long dimensions in tiers about four high. Such a block will conta-in about 1400 retorts, 700 dn each side.

In the operation of such furnaces during the charging, discharging and cleaning of the retorts, there are produced considerable amounts, of dust, smoke and fumes, which must be removed. Heretofore, it has been the practice to mount a hood "or hoods 'over the furnace and projecting on each side, the hoods being connected by flues to a ventilating` stack. The air drawnby the draft of the stack or Ventilating fans carries the dust, fumes, and smoke `away from the furnace, thus enabling the Workmen to do their work without being subjected to 'objectionable conditions. The emission from the stack of the smoke, etc., has, however, in some cases been found to be a nuisance t-o the neighborhood, andit was, therefore, proposed to ob, viate this nuisance by passing the dust-laden gases through a Cottrell dust precipitator. The volume of gases heretofore used was, however, so large that a precipitator of unwieldy size would be required.

Accordingly it is the principal object of this invention to provide an apparatus which will permit the removal of dust and smoke in an efficient and economical manner.

Another object'of the invention is to elimina-te, from the handling of the dust-carry ing gases, all mechanically operated appa-f ratus as well as flues, substituting natural draft for fans and thereby save both initial expense and operating cost.

A further object Of the .invention is to reduce the volume and thus increase thetemperature of the gases so as to give a stronger natural draft, and also to reduce the size of theA dust precipitating equipment.

These objects are attained by an especially' constructed hood and location of the precipilating devicein the natural, direct pass of the dust and fume-laden gases..

My invention consists accordingly of a hood covering the top of the furnace and 1927. Serial No. 187,257.

extending down its Walls, which hood is provided with a throat, or throttle, near the top n of the furnace. A convenient form of providing my hood with such a throat is to' construct this hood with two shells-an outer, straight-walled shell extending downward over the walls of the furnace, and an inner one fitting snug against the furnace walls, bulging or slanting toward the outer shell, near the top of the furnace-and providing at that throat a cross section much smaller than the area of the hood itself and of its'entranceinto the dust precipitating equipment. The inner shell covers also, conveniently, the top of the furnace.

Due to this throat, I am able to considerably reduce the amount of air carried through the hood without, in any way, reducing its function of eliminating the fumes and dust discharged from the furnace during distillation, cleaning, or other operations at the retorts.

At the same time I obtain in the hood a gas of higher temperature which increases the natural draft, and, placing the dust precipitating equipment Within or directly over the hood, that is to say, in direct connection with it, I am able to eliminate all'flues and fans, the precipitating equipment -leading directly into the stacks.

In another form'o'f construction of my novel hood, I provide thev throat with a throttle which permits variations in its cross section. This feature is shown in Fig. 3 of the accompanying drawings.

In an ordinary hood, a strong Wind blowing against one end of the furnace block would result in a very uneven draft., It is quite important, however, in orderV to insure complete and regular elimination of the dust and fumes around the furnace, to provide for an equal draft in the hood over the entire length of the block. l I accomplish this in a preferred embodiment of my invention by making the hoods on each side of the furnace in several, for instance, five or six, sections, and placing a separate Cottrell, or other dust precipitat- `ing device, in approximately the center of each section. This solves lthat difficulty in a very effective and cheap manner; in fact, the cost of construction is less than if on`e large Cottrell were used in the center of t-he block.

The construction of the furnace hood, ac-

show details of the hood con- -entire block, as many like sections being used as are necessary. 1 is the furnace and 2 is the hood which extends over the entire block. 3,-3 are the retorts and 4, 4 are the usual buck-stays. The hood 2 has an outer shell 5 and an inner shell 6, )roviding a passage for delivering the gases into the base of a dustnprecipitator l5, which may be of the usual construction consist-ing, in this partioular instance, of a, square pipe 7 within which are mounted the usual discharge and collecting electrodes` The electrical precipitator thus forms part of the vent stack.

As shown in Figs. 3, 4 and 5, the inner shell of the hood is so shaped as to form, with. a portion of the outer shell, a contraction or throatvS, which is, by means of an adjustable flexible plate'9, or other suitable means, varied in cross-section to control the flow of the gases therethrough. This adjustable plate is fixed at 10 to the inner shell of the hood, but has at its lower ends slots 11, through which pass screw bolts 12 secured to the inner shell.

able. the adjustable plate to be secured in adjusted position. 'lo facilitate adjustment Wing-nuts 13 en-' of the plates, each is provided with a handle bar 14 hinged thereto. By moving the bar -up or' down, the adjustable plates will be bulged outor drawn in to vary the crosssection of the. throat.

The hood is provided with as many adj ustable plates as may be necessary to control the throat opening of the hood and provide for the proper flow of gas for the' varying conditions.

1 is the furnace block covered by a hood, the outer shell of which is shown as 2 and the inner onev as 3; the throat; is indicated by the dotted line 4. f

This hood is divided by the side partitions 5 into six sections. l f

A Cottrell dust eliminator 15 is located in each section; each of them leads into a separate stack 7, the dust obtained in the Cottrells being collected in a connnon screw conveyor 8.

l claim: f

1. A dust and lfurne collecting device for metallurgical furnaces, coinprisinga hood having its lower portion extending over the front of the furnace and having a constricted throat portion above the opening of the hood. v

2. A dust and fume collecting device for metallurgical furnaces, comprising a hoo having its lower portion extending over the front of the furnace and having a constricted throat portion above the opening of the hood, said throat portion being provided with means for varying the opening of the throat.

ln testimony whereof, ll affix my signature.

HENRY nowilnn. 

